Persons with limited mobility, such as the elderly or persons confined to a wheelchair, are susceptible to the development of pressure sores. Pressure sores are formed when the tissue is compressed for extended periods of time causing a restriction in the flow of blood. The exchange of nutrients and waste in the compressed tissue cells is slowed, resulting in skin breakdown and the formation of pressure sores. The retention of heat and moisture are two additional factors that contribute to the formation of pressure sores. Areas most vulnerable to pressure sore formation are bony areas having little tissue between the bone and the skin, including such areas as the ischial tuberosities, coccyx and sacrum.
U.S. Pat. Nos. 4,175,297, 5,103,518, 5,109,560, 5,500,965, 5,839,140, 5, 963,997, 6,014,784, 6,216,299 and 6,668,405 disclose inflatable cushion systems wherein the cushion includes an array of inflatable cells including first and second interconnected groupings of cells interspersed throughout the array which are alternately inflated and deflated on a predetermined schedule in order to vary the location of contact between the cushion and the posterior of a person seated on the cushion.
While effective for reducing the development of discomfort, numbness, pain and pressure sores resulting from prolonged periods of sitting, such cushions are not suitable for use once a pressure sore has developed as the cushion continues to apply at least intermittent pressure upon the affected area causing discomfort, pain and perhaps even exacerbating the sore.
Accordingly, a continuing need exists for an inflatable cushion capable of reducing the pain and discomfort commonly experienced when an individual afflicted with a pressure sore on his/her posterior is seated.